Using vBulletin versions posted here are technically illegal and are only meant for
"try before you buy" purposes but this is and will probably always will be abused,
If you choose to use one from here you do run the risk of getting caught and having your site shutdown.
What normally happens is if you are found using a nulled copy Jelsoft will contact you asking you to close or buy a vaild licence, if you do not do either thay will then contact your host and ask them to remove your files and suspend your hosting account.